Method and machine for testing blades



Jan, 14, 1936. M. KNOBEL ET AL.

METHOD AND MACHINE FOR TESTING BLADES ll Sheets-Sheet 1 Filed. March 19, 1931 INVENTORS 7X4 7% mm BY ATTOR 'EY Jan. 14, 1936.

M. KNOBEL ET AL METHOD AND MACHINE FOR TESTING BLADES 11 Sheets-Sheet 2 Filed March 19, 1931 BYWW 1936. M. KNOBEL ET AL METHOD AND MACHINE FOR TESTING BLADES Filed March 19, 1931 ll Sheets-Sheet 3 INVENTOR5 7% 74 7 y W ,(M 7' y.

AT ORNEY Jan. 14, 1936. M. KNOBEL ET AL METHOD AND MACHINE FOR TESTING BLADES ll Sheets-Sheet 4 Filed. March 19, 1931 ..,|l www M INVENTORS 7 Jan. 14, 1936. M. KNOBEL ET AL METHOD AND MACHINE FOR TESTING BLADES Filed March 19, 195i l1 Sheets-Sheet 5 S7 16 To 14% 0 9 W Jan" 14, 19369 M. KNOBEL. ET AL 9 9 METHOD AND MACHINE FOR TESTING BLADES Filed. March 19, 1931 ll Sheets-Sheet 6 Jan. 14, 1936. M. KNOBEL 1=:r AL

METHOD AND MACHINE FOR TESTING BLADES ll Sheets-Sheet 7 Filed March 19, 1931 Jan. 14, 1936. M. KNOBEL ET AL 2,027,595

METHOD AND MACHINE FOR TESTING BLADES Filed March 19, 1951 ll Sheets-Sheet 8 mmvroxs 71 7/405! M y Zlnu'n AT TNEY l Jan. 14, 1936. M. KNOBEL ET AL 2,027,595

METHOD AND MACHINE FOR TESTING BLADES Filed March 19, 1951 ll Sheets-Sheet 9 'I VENTORS y, 7% 'A-v/ BY W 79 lari mzy Jan. 114,, 1936. M KNOBEL ET AL 2,027,595

METHOD ANDMACHINE FOR TESTING BLADES Filed March 19, 1931 11 Sheets-Sheet 1o INVENTORS 1M, 7/W

BY "24116 W Jan. 14, 1936. M. KNOBEL ET AL METHOD AND MACHINE FOR TESTING BLADES 11 Sheets-Sheet l 1 Filed March 19, 1931 INVENTOR 7 1 'AT'TvEY Patented Jan. 14, 1936 METHOD AND MACHINE FOR TESTING BLADES Max Knobel, Arlington, and Louis H. Young, Auburndale, Mass., assignors to Gillette Safety Razor Company, Boston, Mass, a corporation of Delaware Application March 19, 1931, Serial No. 523,812

43 Claims.

This invention relates to the inspection or testing of blades. The invention will be herein disclosed as embodied in a machine for testing safety razor blades of the well known double edged type, but it will be evident that many features of the invention are equally applicable to machines or apparatus for testing other kinds of blades.

When the manufacturing operations on safety razor blades have been completed, the blades then are subjected toa series of inspections or tests designed to detect faults or imperfections. Of these tests, those which have to do with the condition of the blade edge or edges not only are especially important, but are the most difficult to make satisfactorily in routine production. The nature of a razor blade edge is such that inspection for defects in its sharpness presents unusual difficulties. The old method of testing a blade edge by cutting a hair with it is still, so far as we are aware, the most satisfactory, and it is the method most commonly used. Due to the fact, however, that this inspection or test must be performed by hand, it is necessarily relatively slow and is correspondingly expensive. Such a test also is accompanied by some danger to the inspectors due to the nature of the articles handled. Furthermore, the human factor introduces variations in results which are unavoidable, as a practical matter, so that blades which have passed inspection are not always up to the desired standard.

The present invention deals especially with this problem.It aims to improve both the methods of, and the mechanism for, testing the sharpness of blade edges with a view to reducing the expense involved in this operation, and more especially, to producing more uniform results and making a more nearly perfect inspection.

Any substantial variation in the width of a safety razor blade, especially one of the double edged type, is objectionable because of its effect on the exposure of the edge with reference to the cap and guard of the blade holder. This exposure, or degree of projection of the blade edge beyond the cap, has a very important effect on the shaving qualities of the razor. The usual method of measuring the width of small articles such as blades is to caliper them but it obviously is impossible to caliper a sharpened safety razor blade without great danger of ruining the cutting edge. At the present time no entirely satisfactory method of inspecting the width of safety razor blades is available, so far as we are aware, which is suitable for use in factory production. It has, therefore, been the usual practice so to control the manufacturing operations as to minimize variations in width, so far as possible, and only very obvious variations in width have received attention in the final inspection.

It is a further object of this invention to devise a thoroughly practical mechanism for performing this testing or inspecting operation which will not only be extremely accurate, but which will perform this operation rapidly, and whichwill largely eliminate hand labor. The invention also involves a novel method of inspecting safety razor blades for width. It may here be noted, however, that the width inspection involves examination of the edges of the blade, and it is contemplated that this inspection or testing operation will have many features in common with that of testing the sharpness of the edges.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawings, and the novel features will be particularly pointed out in the appended claims.

In the drawings,

Figure 1 is a perspective view of a machine constructed in accordance with this invention;

Fig. 2 is a partial elevation indicating somewhat diagrammatically the arrangement of various units on the shaft at the right-hand end of the machine as shown in Fig. 1;

Figs. 3 and 4 are front elevations of sections of the machine shown in Fig. 1;

Fig. 5 is a sectional perspective view of one of the units for testing the sharpness of the edges of the blades;

Fig. 6 is a plan view of a portion of the appa ratus shown in Fig. 5;

Figs. 7 and 8 are sectional views illustrating details of construction of the apparatus shown in Fig. 5;

Fig. 9 is a vertical longitudinal sectional view illustrating features of the mechanism for testing the width of the blades;

Fig. 10 is a plan view illustrating details of the construction of said mechanism;

Fig. 11 is a perspective view of the automatic switch for controlling the lamp used in the width testing apparatus;

Fig. 12 is a vertical, transverse, sectional view on a large scale showing features of the width testing apparatus;

Figs. 13 and 14 are side and perspective views, respectively, of the automatic mechanismfor placing the blades on the conveyor belt;

Figs. 15 and 16 are side and sectional view, respectively, of valves for controlling the admission of vacuum to the blade handling mechanisms;

Figs. 17 and 18 are diagrams of the electrical connections used in the machine;

Fig. 19 is a' side view illustrating certain features of the blade handling mechanism; and

Fig. 20 is a perspective view of parts of the connection for enabling the testing devices to control the blade sorting operation.

General statement As above indicated, the machine shown in the drawings is designed especially to handle double edged safety razor blades and to perform the operations of testing the sharpness of both edges of each @lade and the width of the blades, and subsequently sorting the blades to separate those blades which successfully pass the tests from those which-are rejected. Briefly stated, the machine shown comprises a conveyor for carrying the blades to and from the testing devices, mechanism for placing the blades one at a time on the conveyor, devices for testing the sharpness of both edges, two separate devices for this purpose being provided in the present machine, a device for testing, the width of the blades, mechanisms for removing the rejected blades from the conveyor, connections for causing the respective testing devices to control the operation of the blade removing mechanisms, and means for removing from the conveyor the .blades which successfully pass the tests. The detailed description of the various features of the machine will be taken up in substantially the order in which they have just been men-' tioned.

Conveyor Referring first to Figs. 1, 3 and 4, the'blade conveyor consists of a metal belt 2 supported on two pulleys 3 and 4, respectively, the pulley 3 having a series of short pins 3, Fig. 1, projecting from its periphery to enter holes 6 in the belt in order to drive the. belt positively. The belt carries a series of pins 1, best shown in Fig. 10, arranged in pairs, the individual pins of each pair being properly spaced to fit in an internal aperture in the blades 3 so that the blades, in addition to being transferred or conveyed by the belt are definitely and positively positioned on the belt by internal contact which leaves the sharpened edges. freely exposed for the testing operations to be performed thereon.

The driving mechanism for the conveyor ,com-

' prises a worm wheel 8 fast on the shaft In on the end of a shaftl2 which extends substantially the entire length of the machine." At the end of the machine opposite to the worm H the shaft I2 is equipped with a pulley to receive a driving belt 13, Fig. 3. designed to drive the conveyor belt at a slow and substantially uniformspeed. 4

All of the testing operations are performed Oll'thfi blades while they are carried along on the upper reach of the conveyor belt, and in order to guide them in the desired path and to prevent the sag in of the belt, a guide or rail It is provided for it, the belt running in a groove t5, Fig. 8, formed in the upper surface of this rail.

pulley 3 is secured and a worm H for This mechanism is At several poi its along the rail 7 port being connected through the 1I\pe"or tube a guard is-placed over the belt, as shown at If in Figs. 5 and 8, the guard having a groove I1, Fig. 8, in its lower surface to permit the passage of the pins 1 and being spaced from the rail 14 by a distance slightly greater than the width of he belt. 5

Blade feeding and positioning mechanism L At the station A, Figs. 1 and 3, a mechanism is provided for placing blades to be tested one at a time on the conveyor belt. This mechanism is best shown in Figs. 13, 14 and 19 and is constructed and arranged to operate in a similar manner to the blade handling mechanism shown .in Patent No. 1,255,917, granted February 12,

1918. It comprises a magazine plate 20 having 15 a series of pins 2| arranged in pairs, each pair being adapted to support a stack of blades '9. A suction pickup mechanism is provided to take blades one at a time from the top of the stack and transfer them to the belt 2. This pickup mechanism is of a known form and comprises a suction head 22 shaped for contact with the blades and mounted on an arm 23 which is supported on theupper end of an upright barrel pinion 24. A rackf25 meshes with this pinion and is connected with a roll 28, Fig. 13, running in a path 21 of a cam 28 fast on a horizontal shaft 30, this cam path being designed to move the pinion far enough to swing the suction head 22 from a position in line with the pair of pins 2| which holds the blades 9, into another position in line with, and directly over, the conveyor belt 2. The suction head is also/given an up and down movement through connections with a second, cam 29 fast on the shaft 30 andlocated immediately beside the cam 28, these connections including a lever 3|, Fig. 13, carrying at one end a roll 32 which runs in the cam path. At its opposite end this lever is pivoted to a rod or pin 33 which extends into the lower part of the pinion 24 without interfering with the rotarymovement of the pinion.

The suction head 22 and arm 23 are made hollow and communicate with a nipple 34 to which a flexible tube 35 is connected, the latter-tube running to a pipe 36, Figs. -3 and 4,

whieh'leads from a valve 31, Figs. 1 and 4, that controls the admission of'suction to the pipe 38.

Referring to Figs. 1, 2, 4, 15 and -16, it will be seen that the valve 31, together with certain other valves of a similar construction, are supported on a disk 38 which is mounted on the shaft 18, the disk, however, being'held. against rotation. Immediately beside the disk 38 and secured o'npthe shaft 18 to rotate therewith, is another disk 43 carrying a series of pins 41 which project toward the stationary disk 38. Each of these pins is adapted to engage with. a roll 42, Figs. 15 and 16, carried by a short lever- 43 which is fulcrumed on part of the valve. (1563 casing, and such engagement serves to lift the lever 43. The valve includes a plunger 44 sliding in the bore of the valve casing 31 and hav-' ,ing a pin or rod 43 projecting from'its lower. -end and resting on the valve 43, a spring,

pressing the plunger downwardly. Iii-its low- .ered position the valve plunger 44 does navquite 3| with a vacuum header 52, Fig. i.

accuses Thetiming of the movements of the suction head and of the valve are such that when the suction head 22 is brought down upon the top of the stack of blades shown in Fig. 13, the suc- 1 suction valve plunger ll closes the port 5b and opens the port il to the atmosphere, thus causing the suction head 22 to release the blade.

At this instant, also, a short pufi of compressed air is delivered through a nozzle 53, Figs. 13 and 14, immediately above the blade which has just beentransferred by the suction lid tilt

head, this pufi serving to ensure the release of the blade by the suction head. It is usually found advantageousalso to direct a similar pull of compressed air against the side of the stack of blades and close to the uppermost blade at the instant that the suction head picks up the latter blade so as to prevent the picking up of two blades at a time. Such a puff or jet of compressed air may be delivered through a nozzle t l, Fig. 14. Both compressed air nozzles lit and ti l are connected to a compressed air supply line through a valve v arranged to be operated by a cam ill, Fig. 19, on the shaft 4 When the suction head has been swung into position over the stack of blades and is allowed to drop by the lever iii, the whole suction head and the barrel pinion which carries it, drops under the influence of gravity until the suction head strikes the uppermost blade in the staclr. This movement is permitted by the shape of the operating earn fill, Fig. 19, and permits the movement of the suction head to accommodate itself to changes in height of the stack of blades. Because of these changes in height it is necessary also to adjust the nozzle 56 to p sition it at the desired level when a blade is picked off the stack, and this may conveniently be accomplished by supporting the nozzle on an arm tll Flg. it, which is carried by a post ill supported in a socket formed in a boss A spring (not shown) acts on the post bl to hold thearm (it! and nozzle 5d normally in a raised position. When, however, the suction head arm 23 is swung into position over the stack-oi blades, it then overlies the arm ht) so that upon its downward movement it depresses the arm (ill, and consequently the nozzle 56, movingthe latter down to a level depending upon the degree of its own lowering movement. Thus the nozzle always is positioned properly to deliver its jetpf air at a point between the blade which the head is picking up and the next lower blade. I

It will be observed that the suction head 22 should travel with the conveyor belt 2 during the short interval in which it deposits a blade on the belt. This is accomplished by mounting the entire pickup mechanism and its cams for movement in unison with the belt 2 during the brief interval required to position a blade on the belt. For this purpose most of the parts just described are supported on a plate t l,Fig. 13, the forward end of which is mounted to slide in a horizontal guideway ch in one of the rail sections i l, which in this case forms a part of the machine frame. The rearward end of this plate is provided with two arms, one of which is indicated at M, Figs. 1 and 13 and both of which embrace the shaft 3b, these arms thus being supportedmn the shaft. Suitable collars are secured to the shaft to prevent the arms from moving longitudinally with relation to it, and the entire shaft is reciprocated at the proper point in the cycle of operations of the pickup mechanism to move the plate and the pickup mechanism in unison with the belt '2, thisoperation being performed by a cam ill, Fig. 3, fast on the end of the shaft til. The groove of this cam is engaged by a roll til mounted to revolve on a fixed axis. A train of gears ill, Fig. 3, operatively connects the shaft 3b with the ,shaft it, previously referred to, to drive the former shaft.

When the supply of blades in any staclr on the plate lit, Fig. 14, becomes depleted, the plate may be rotated to bring another stack into operative relationship tothe suction head, this rotating operation being performed by hand. Normally the plate to is locked in a stationary position by the dog l i, Fig. 14.

This mechanism thus operates to take blades from a supply and place them one at a time at each successive pair of pins on the belt 2 as the belt continues to move uninterruptedly.

. Sharpness testing apparatus The blades next pass into the first edge test- Figs'. 1 and 3. Referring more particularly to Figs. 5 to 7, inclusive, it will be seen that this device. or apparatus comprises a casing it through which the traclr it runs. The casing is nearly light tight and is provided at one side with a supplemental casing it for enclosing a lamp ill. The rays of this lamp are condensed or focused by lenses, one of which is shown at it, to direct a strong beam of light through a slot it, upon the edge of each blade 9 as the blades come successively into testing position. lit will be observed that the beam of light so directed on the blade is confined chiefly to the edge portion of the blade and strikes the margin of the blade from above and at a considerable angle. the edge of a properly sharpened blade is substantially a line, it is evident that very little light will be reflected from, or scattered by, asharp edge; but that any defects in the edge, such as nicks, dull spots or turnedover portions will reflect a very much larger percentage of the light. A light sensitive resistance element oi some kind, such as a photoelectric cell, selenium cell, or the like, indicated at ll, is located in a compartment of the casing where it can see the edge of a blade ii in testing position but is substantially protected from stray light, or in fact from light coming from any other source than the vicinity of the blade edge. This protection is afiorded by partitions lb and lit in the casing it, a narrow slot El being out through the latter partition to permit the cell ll to receive only rays coming from the direction of the blade edge.

, As successive blades pass through the testing position the intensity of the light reflected from their edges on to the photo-electric cell ill, will vary with the degree of sharpness .of successive edges. Consequently, the conductivity of the cell ll will vary with such variations in sharpness. By connecting this cell in an electric circuit in which some suitable indicating device also is included, these variations in, sharpness can be made to cause corresponding variations in ouring apparatus which is located at the station E,

ii I

next station C, Fig. 3, where the blades rejected in the first sharpness testing operation are removed from the belt, and it carries the blades which pass this inspection to the second sharpness testing operation which is performed at the station D. The apparatus which makes this test is a duplicate of that above described at the station B, but the arrangement of the elements is reversed so that they operate on the edges of the blades opposite to those previously tested. No detailed description of this apparatus, therefore, is required. It may here be pointed out, however, that these two testing mechanisms could be combined in a single casing and both tests made either successively or substantially simultaneously, as desired.

Theblades next are carried by the conveyor to the station E where another pickup mechanism is located under the control of the preceding sharpness testing mechanism to remove those blades from the conveyor which have been rejected in said test or inspection.

Blad'e removing mechanisms controlled by sharpness testing units and control connections 1 The two pickup mechanisms located at stations C and E are each substantially like that above described at the station A. They operate to pick up blades from the conveyor belt 2 and to stack them on magazine plates 82 and 83, respectively, Fig. 1, like the magazine plate 20, Fig. 14. Each of these pickup mechanisms is operated from the shaft 30 by cams like those previously described and they differ from the pickup mechanisms above described chiefly in that the timing of the application of suction to their respective suction heads is somewhat different, as will be obvious, and in the further fact that each has a single blower nozzle only arranged to direct a short puff of air against the blade carried by the suction head when the suction is cut off to cause the pickup mechanism to release the blade and deposit in on the stack. The valve for-controlling this application of compressed air to the two nozzles of the pickup mechanisms at the stations C and E is shown at 84, Fig. 1, and is arranged to be operated by the cam 85 on the shaft 30. This valve also controls the application of compressed air to each of the other pickup mechanisms which will later be described, since all of these mechanisms operate in unison.

It will be understood that all of the pickup mechanisms go through their cycle of operations once during each rotation of the shaft Whether either of the mechanisms at'the stations C and E remove a blade from the conveyor belt 2, however, depends upon the applithose blades which are rejected by the respective sharpness testing units B and D immediately preceding them. In other words, each of the pickups at the latter stations are under the control of the respective sharpness testing units. In the particular arrangement shown in the drawings this control is efiected by controlling .the operation of the suction valves for the respective pickup mechanisms at the stations 0 and E. These valves are indicated, respectively, at 86 and 81, Fig. 4. They are both mounted on a disk 88, Figs. 1 and 2, similar to :the disk 38, which is supported on the shaft l0 but is held against rotation. Each of these valves is substantially like the valve 31 shown in Figs. and 16 and several such valves are mounted on the supporting disk 88. They are arranged to be operated selectively by pins 90, Figs. 1, 2 and 20, carried by a disk 9| which is secured fast on the shaft In. Each pin 90 is slidably mounted in the disk 9| for movement in a direction parallel to the axis of the disk, and it is provided at its left-hand end, Figs. 2 and 20, with a head 92 which projects beyond the face of the disk. A spring 93, Fig. 2, is associated with each pin and tends to project it toward the right. in its retracted position, as shown in Fig. 2, by means of a spring actuated latch 94 pivoted on the face of the disk 9|, one latch being provided for each pin.

As above stated, each of the sharpness indicating units includes alight sensitive element located in an electric circuit, as will shortly be described more in detail. This circuit controls the operation of an electro-magnet like that shown at 95, Fig. 20, one of these magnets being operatively associated with each of the valves carried by the disk 88. In this particular machine four such valves are used and four electro-rnagnets therefore are employed. All of these magnets are adjustably mounted on a stationary disk 96 which is supported on the shaft l0 but is held against rotation.

Normally the coil of each of these magnets is energized so that the core 91, Fig. 20, of the magnet is held in a retracted position. When either of the sharpness testing devices indicates that a blade should be rejected, the magnet 95 for that particular testing device is momen- Normally, however, each pin is held tarily deenergized, and the core 91 for the magnet is thereupon projected by springs 98-98, Fig. 20, associated with it. The projected core or plunger strikes one of the latches 94, thus releasing the pin 90 previously held by it and allows the spring 92 for this pin to move the pin toward the right, Fig. 2, far enough to operate the lever for the next suction valve ahead of it.

\ It will be observed that an appreciable interval of time occurs between the testing of the edge of any blade and the arrival of that blade in position to be picked off the conveyor by the next pickup mechanism. Consequently, the action of the pickup mechanism associated with each of the edge testing units must be delayed long enough to enable the blades, respectively, toarriveincooperative relationship to the pickups. This delayed action is obtained by so spacing the solenoids or electro-magnets 95 with reference to the suction valves for the respective pickups that the conveyor belt 2 can travel the desired distance before the suction valves are operated by the'pins 90. In other words, the defective blade indication is given simultaneously with the testing of the blade, and at substantially the same instant the plunger 91 is projected and operates a latch 94 to release a pin 90. This pin, however, travels with the disk 9| for-a predetermined distance before it operates the suction valve associated with the particular soletion on the rim'of the disk 88, and as it passes the roll it is pushed back by the roll far enough to allow its latch 94 to engage and lock it in its retracted position. This occurs before the pin has travelled far enough to operate another suction valve.

Circuit arrangement of control connections A suitable circuit arrangement for use in the control connections between the sharpness testing devices and the solenoids 95 is shown diagrammatically in Fig. 17. In addition to the photoelectric cell ll previously referred to, these connections also include a tube E02, similar to those used in radio work. The particular tube shown is of .the screen grid type and-the tube known commercially as UK 224 may be used for this purpose. Power for operating the-apparatus may conveniently be supplied through a B battery eliminator M8, the supply conductors for this device being shown at ltd. For purposes of explanation it may be assumed that two hundred volts direct current are delivered across the terminals hi and a much smaller voltage, say three volts, across the terminals the.

The tube an includes a positive electrode or anode consisting of a plate till, a screen grid it, a control grid ltd, a cathode lit, and a filament M2. The plate lull is connected to the positive terminal ltd, preferably through a milliammeter M3 and a relay instrument Md. Three potentiometers M5, M6 and iii are connected in series directly across the terminals m5, and the adjustable contacts of these devices are connected by suitable conductors to other elements of the circuit. These potentiometers should be of high value, those indicated at M5 and Mt each being, say, ten thousand ohms, while that indicated at ill may be twenty-five hundred i'uy. As

shown, the adjustable contact of the potentiometer M5 is connected directly to the screen grid tut, while that of the potentiometer Mt is connected through a battery M8 to the positive terminal of the photoelectric cell W, and that of the potentiometer ill is connected through a C battery E20 and a high non inductive resistance iii to the control grid tilt, this grid also being connected directly to the negative terminal of the photoelectric cell. The battery H8 should have a relatively high value, say for example, sixty-five or seventy volts, while the C battery tit may be ab out four or five volts. The reslst= ance l2i should have a value of tour or flve megohms. The filament M2 is connected directly to the terminals [1% of the B battery eliminator.

When the testing machine is in operation, the various elements of the system are so adjusted that a small plate current flows continuously through the meter M3 and instrument ti l. As-

suming that no'blade is in testing position thisv current may take a value of approximately one milliampere. When a blade is brought into test- 'plication filed by us.

ing position and the beam of light from the lamp 14, Fig. 5, is directed against its edge, the light reflected from the edge, if the bladejs sharp, will not be suficient to increase appreciably the plate current flowing through the circuit just mentioned. The plate current will vary, however, with variations in the intensity of the light reflected from the edges of successive blades being tested, and if a blade is dull a very substantial increase in plate current will thereby be produced. This increase in current occurs due to the increase in conductivity of the photoelectric cell 11 and a consequent change in. the voltage of the control grid I09, as will be readily understood by those skilled in this art.

The instrument I I4 is essentially a milliammeter with a small mirror H9 mounted on its armature. A beam of light from the lamp I23 is Hirected constantly against this mirror and may be reflected from the mirror through a series of apertures in the box 24 against a selenium cell l25. An arm I26 rigid with the armature of the instrument i it is arranged to swing between adjusting screws E27, and in the preferred arrangement these screws are so set that so long as the current flowing through the plate circuit remains below a predetermined value, say for example one milliampere, the arm H26 will be held against one of the screws ill, and the beam of light reflected from the mirror will not illuminate the selenium cell 125.

The circuit arrangement in which the selenium cell B25 is included cooperates with the instrument M l to act as a relay for amplifying very substantially the current variations in the plate circuit of the tube are, and this relay organization forms the subject matter of a pending ap- For present purposes a brief description only of this circuit arrangement is necessary. It comprises a grid controlled vacuum or gas filled tube indicated at ltd. Preferably, but not necessarily, a screen grid tube filled with mercury vapor is used. This tube has a positive electrode or anode consisting of a plate iii, a filament E32, a cathode tilt, and a grid ltd, all these parts being enclosed in an evacuated glass envelope equipped with suitable terminals. A tube known commercially as the Thyratron gives good iresults. The power supply consists of a transformer including a primary coil H35 and a secondary divided into sections,

one of which is indicated at 936, and is designed to supply a potential of, say, one hundred ten volts, while another, indicated at fltll, is intended to supply, say, five volts for heating the filament 032. Still another section i363 may give a voltage of approximately twenty volts, while the fourth section Illt is utilized to heat the filament of the lamp i233 previously referred to.

A high non-inductive resistance Mill, and if desired also a condenser M2, are connected in series with the selenium cell F125, and together are connected across the secondary coils tilt and list. The grid tilt is connected to a point bee tween the cell i255 and the condenser M2.

With this arrangement, therefore, the potential of the-grid will be controlled by the resist ance of the selenium cell i225, and this control is such that current will flow through the tube ltli so long as the cell 625 is not illuminated, but

such flow of current will be interrupted by the illumination of the cell. it will be observed that the coil of one of the electro-inagnets, previously referred to, is in series with the plate 138 of the tube lit] so that this coil normally is one ergized and becomes deenergized only when the sharpness testing unit with which it is connected indicates a dull blade. As just explained, such an indication involves an increase in the flow of current through the instruments H3 and H4 sufl'icient to cause the mirror H9 in the latter instrument to shift the beam of light on to the cell I25, thus causing the tube I30 to go out, or, in other words, to stop conducting. Preferably the adjustment of the screws I21 in the instrument H4 is such that while, as above stated, the beam of light reflected by the mirror does not strike the selenium cell until the current flowing through the plate circuit of the tube I02 rises to a substantially predetermined value, currents above that value operate simply to maintain the beam of light on the cell I25. The cell is so enclosed in the box I24 that it is amply protected from stray light.

Each of the sharpness testing units is con,- nected with its respective electro-magnet coil by an electrical apparatus like that shown in Fig. 17. While a part, of this apparatus operates as a relay, it should benoted that such operation does not depend upon movable contacts which must be opened or closed. The arrangement is, therefore, extremely reliable and a very high degree of amplification is obtainable. For example, we have found that current fluctuations in the test circuit of in the neighborhood of one-one hundredth of a milliampere may be made to cause a current of one or two amperes to flow through the plate circuit of the tube I30 and consequently through the solenoid 95. Even higher amperages'in the latter circuit can be similarly controlled. It will be understood that in speaking of the test circuit we mean the circuit in which the milliammeter H3 and instrument H4 are connected.

Width testing apparatus The width testing unit is located at the station F, Figs. 1 and 4, the elements which perform this testing operation being enclosed in a casing I44. These elements are best shown in Figs. 9, 10 and 12. As the blades 9 are carried along by the belt 2 into the casing I44 they are brought successively under a plate I45 in which are formed two narrow parallel slots I46. The

center lines of these slots are spaced apart by.

a distance equal to the spacing of the edges of a blade of the correct width. These slots lie directly under a fairly large incandescent lamp I41 which directs strong beams of light downwardly through the slots I46 and against the edges of a blade 9 located in position to have its width tested. More or less of these beams of light are intercepted or cut off by the edges of the blades depending, of course, upon variations in the width of the blades. Those fractions of the beams which pass the blade edges travel downwardly through slots I48I48 in the underlying and supporting plate I50 and strike, respectively, inclined mirrors or reflecting surfaces I5I-I5I which reflect the light so received upon a photoelectric cell or other light sensitive resistance element I52.

Since the intensity of the light which will be received by the photocell I52 will depend upon variations in the .widths of successive blades brought into testing position, and since the conductivity of the photocell will depend upon the degree of illumination which it receives, this cell can be used in an electric circuit to control the operation of indicating and sorting apparatus in essentially the same manner that the photocell I1 is used in connection with the sharpness testing units.

A circuit arrangement suitable for this purpose is illustrated in Fig. 18. The testing circuit there shown is like that illustrated in Fig. 17 except that the tube I53 which takes the place of the tube I02 in Fig. 17 is of a slightly different type in which it uses the filament I54 as the cathode. It includes a plate anode I55, a shield grid I56 and a control grid I5"! which perform essentially the same functions as the corresponding elements in the tube I02. A tube known commercially as UK 222 may be used with satisfactory results at I53. Power may conveniently be supplied to the apparatus by a B battery eliminator I58 and the circuit connections as shown in Fig. 18 are identical with those shown in Fig. 17 except that the cathode connection from the potentiometer H1 is made to the middle point of an impedance coil I60 which is connected across the terminals of the filament I54, this arrangement being common in using tubes of.

the type illustrated. The plate circuit or testing circuit also includes a milliammeter I6I having a range of, say, 1.5 milliamperes like the milliammeter H3 of the circuit prevously described, and an instrument I62 like that shown at H4 in Fig. 17.

The relay circuit shown in Fig. 18 is substantially like that shown in Fig. 1'7 except that it involves a duplex arrangement. This is made necessary by the fact that it is desirable to reject those blades which are too narrow as well as those blades which are too wide. This circuit arrangement therefore includes two tubes I63 and I64 which may be like the tube I30, Fig. 17, and which are connected in parallel. Two selenium cells I65 and I66 are connected with the respective tubes I63 and I64 in the same manner that the cell I25 is connected with the tube I30. Each cell is utilized to control the grid voltage of its respective tube and serves, therefore, to cut the tube out of operation .or to make it stop conducting when the cell is illuminated. Both selenium cells are located in a housing or casing I61 which protects them from stray light, this casing having suitably alined apertures to admit the beam of light reflected from the mirror I68 of the instrument I62. A small lamp I10 throws a beam of light upon the mirror I68. Two solenoids or electro-magnet coils 95 are connected in the plate circuits of the two tubes I63,and I64, each of these solenoids controlling a plunger or core which is adapted to operate a latch 94, as in the construction shown in Fig. 17.

With this arrangement when a razor blade is brought into testing position under the lamp I41 the photocell I52, Fig. 12, will see both edges of the blade simultaneously. If the intensity of thelight which it receives is below a predetermined amount, the mirror I68 will be swung into position to illuminate one of the selenium cells I65 or I66, thus indicating that the blade should be rejected. This rejection is effected by the deenergization of the solenoid 95 which is under the control of the cell so illuminated and the tube associated with it. If

the blade in testing position is too narrow, a

much greater quantity of light will be directed upon the photocell I52, thus causing the mirror I68 to swing in the opposite direction far enough to illuminate the other selenium cell and thereby to effect the deenergization of the solenoid 95 aerator connected with it. If, however, the blade in testing. position is of substantially the correct width, then the beam of light reflected from the mirror not will occupy an intermediate position and will not illuminate either of the selenium cells 065 or Mill;

The pickup mechanisms controlled by the width testing unit are shown at the stations G and H, Figs. 1 and 4; and the suction valves for them are shown at ill and W2, respectively,

Fig. i. As above indicated, one of these pick ups removes only blades which are too wide and the other only blades which are too narrow.

Those blades which successfully pass all the tests are removed by the pickup mechanism lo cated at the station I. The suction valve for this pickup is indicated in Fig. 4 at. tilt, this valve being mounted on the disk 38 and being operated by pins ill on the disk til.

It may here be pointed out that while the width measuring unit illustrated in Fig. 2 measures the extreme width of the-blades, the dimension to be measured will vary with blades of different constructions. For example, in a single edge blade the overall width may either be important or not, depending upon the manner in which the blade is positioned in the holder. If it is located by positioning pins, then the width to. be measured obviously will be the distance between the pins and the blade edge. The unit shown in Fig. 12 may also be said to measure this width since each blade is positioned by the pins 77 on the belt 2, and variations in the distance between the' pins and either edge or the blade will produce corresponding variations in the width of the beam of light inter= cepted by that edge. Due, however, to the fact that these blades are double edged, this particular unit has been arranged to use the sum of the light rays passing both edges. This would not be the case it independent photocells were used for both edges.

This apparatus has the advantage oi being extremely accurate, very reliable, and of avoiding any necessity for handling the blades man= ually or touching either edge. Any liability of injuring the edges in performing the width test ing operation therefore is effectually avoided.

As the end oi a blade moves into or out of testing position a considerably greater quantity of light is allowed to strike the photoelectric cell it? due to the tact that a much smaller pro portion of the slots t lt are covered by the blade than is the ewe when a blade is in testing position. During these times, therefore, the cur rent in the testing circuit is abnormally high and consequently the mirror M58 tends to swing into a position where it indicates too narrow a blade. In order to prevent the actuation or the mechanism during these periods, a switch consisting of two spring contacts are and ltl, Figs. 11 and i8, is connected into'one side of the power circuit leading to the selenium cells its and tilt, and this switch is arranged to be oper ated automatically by a cam its fast on the shaft 3b. A lever 0922, Figs. 1 and 11, has about end resting on the cam E93, the lever being held against the periphery of the cam' by a spring we. This lever carries an insulating arm set which is arranged to engage at times with the upper contact tilt and force it downwardly into engagement with the lower contact ltl, thus closing the circuit through the selenium cells 655 and let. This action occurs only when the end of the lever 992 drops into a notch Wt in the cam W3 and the timing of the cam is made such thatthe circuit is closed only when a blade is in proper testing position, the switch remaining open at all other times. So long as this switch is open the tubes M3 and lo l continue to conduct current or remain on, regardless of whether or not the selenium cells are illuminated, and current therefore keeps flowing through the two solenoids 95 in series, respectively, with said tubes. Consequently, the electrical circuit of the sorting mechanism controlled by the width testing unit is held in an inactive condition, sofar as the sorting function is concerned, at all times except during U those periods in which blades are properly positioned for the width testing operation. This may result in" very short lengths of the sharpenededges of the blade at each end not being tested for width, but these untested parts are so short that they can be safely disregarded.

Shutter for sharpness testing unit The sharpness testing units above described are designed to illuminate a small section only of a blade edge at a. time, the blade passing through the beam of light directed on it during the testing operation. It is desirable to prevent the beam of light from striking those portions of the blade at opposite ends of the sharpened edge since these parts of the blade are not intended to be sharpened and if illuminated would operate through the photocell and the connections controlled thereby to reject the blade even though its edge were up to the edge required standard. It is contemplated that the entire sharpened edge of a blade could be illuminated. simultaneously, but even with an apparatus so organized it would still be desirable to prevent illumination of the unsharpened end portions of v the blade.

This may be accomplished in various ways.

In the construction shown in 5, 6 and '2 a shutter tilt is arranged to slide up and down across the aperture it through which the beam a rod tilt which slides vertically in guides se cured to thecasing it, the upper end portion of the rod being bent to provide a horizontal arm lit overlying the casing All. A small upright rod tilt is pivotally connected to the shutter i715 and extends upwardly through the casing top and through an eye in the horizontal arm tilt. This rod is encircled by a spring ltl which bears against the arm we and is backed up by a nut m2 threaded on the upper end of the rod. The shaft 3i makes one complete revolution in. each cycle of operations of the machine and therefore during the testing of each blade edge, and the cam Hit is timed to liftthe shutter llt and to drop it again at the correct instants to accomplish the result above described.

, In order to prevent this mechanism from open ing the shutter when no blade is in testing posi= tion, the shutter H5 is equipped with a stop or lug its arranged to be engaged by a latch 8842 which is pivoted on the shutter guide. This latch has the form of a bell crank lever, as

As shown, the lifting shown in Fig. 7, and its upper arm is arranged to be engaged by an arm I85 secured fast on one end of a short shaft I86. A fe'eler I8'I is secured fast to the opposite end of this shaft where it will be engaged and lifted by the margin of each blade'as the blade is moved into testing position. If, therefore, a blade fails to come into testing position the latch I84 will hold the shutter I closed notwithstanding the action of the cam I16, the movement of the rod I18 produced by this cam resulting simply in compressing the spring I8I. Normally, however, as each blade moves into testing position, it operates through the feeler I81, shaft I86 and arm I85 to swing the latch I84 in a counter-clockwise direction, Fig. 7, where it releases the stop I83 and permits the cam IIB to open the shutter.

Operation The machine is entirely automatic in its operation, the attendant being required simply to keep a proper supply of blades in the magazine of the first pickup mechanism at the station A and to remove the rejected blades and those blades which pass the test successfully. The blades are placed on the conveyor belt at the first station and are carried by it through the different testing devices, the pickups removing the blades at various points along their path of travel in accordance with the results of the testing operations, and the accepted blades finally being taken off at the station I. The manner in which the various units operate has been explained so fully in connection with the foregoing description that no further statement as to their operation is believed to be necessary. In both the sharpness testing units and also in the width testing device, variations in sharpness of successive edges and in the width of successive blades are respectively caused to create corresponding variations in current flowin an electric circuit, and the current fluctuations so produced are utilized to separate the blades which are satisfactoryfrom those which are not.

In view of the fact that certain of the tests may be affected by the presence of dust particles carried by the edges of the blades, the machine shown has been equipped with a mechanism I91, Fig. 3, for wiping or cleaning the edges of the blades before they go into the first testing unit. This mechanism consists simply of belts for wiping the bevelled surfaces of the blades in a manner similar to that used in certain stropping machines.

We have found in practice that the machine can handle the blades rapidly, and that the testing operations are performed with an unusually high degree of accuracy. The results are far more uniform than those produced by the manual testing methods heretofore generally employed. At the same time the expense of performing the testing operations is reduced very substantially.

While we have herein shown and described a preferred embodiment of our invention, it will be evident that the invention may be embodied in other forms without departing from the spirit or scope thereof. Also, that the invention is not limited to the conjoint use of its various features herein disclosed. For example, it is contemplated that the width testing and sharpness testing mechanisms may be used independently of each other, the blades being tested for width after the grinding operation has-been performed and those blades which successfully pass this test then being carried through'the remaining manufacturing operations before their edges are tested for sharpness. In this way many of the manufacturing operations on those blades which are too wide or too narrow will be eliminated.

It will also be understood that while certain specific voltages, resistances, and the like have been referred to above, that such references have been made simply by way of illustration and for purposes of explanation, and that factors of this character as well as the nature and arrangement of the parts necessarily will be determined by the requirements of individual cases. It is further noted that the term powerdriven is used herein in a broad sense and particularly to'distinguish from the hand operation of devices by an operator.

Having thus described our invention, what we desire to claim as new is:

1. That improvement in methods of detecting variations in the sharpness of blade edges which consists in directing a beam of light successively against the edges of a series of blades, and measuring variations in the intensity of the light reflected from successive edges.

2. That improvement in methods of detecting variations in the sharpness of blade edges which consists in directing a beam of light successively against the edges of a series of blades, and utilizing variations of predetermined degree in the intensity of the light reflected from successive edges to indicate relative degrees of sharpness.

3. That improvement in methods of detecting variations in the sharpness of blade edges which consists in illuminating successively the edges of a series of blades, whereby the light reflected by successive edges will vary' with variations in the sharpness of successive edges, and causing said variations in reflected light to produce effects depending upon the degree of the latter variations.

4. That improvement in methods of detecting variations in the sharpness of different parts of a blade edge which consists in passing the edge of a blade through a beam of light, and causing variations in the light reflected by successive portions of the edge to produce effects depending upon the degree of the latter variations.

5. That improvement in methods of testing the sharpness of a blade edge which consists in directing a beam of light against said edge, causing the light reflected from said edge to control the flow of current through an electric circuit,

and utilizing said current fiow to give an indication of the relative sharpness of said edge.

6. That improvement in methods of detecting variations in the sharpness of blade edges which consists in passing the edges of a series of blades successively through a beam of light, and measuring variations in the intensity of the light reflected from successive edges.

7. That improvement in methods of detecting variations in the sharpness of blade edges which consists in directing a beam of light against the edges of a continuously moving series of blades,

and utilizing variations in the light reflected from said edges to give relative indications of the sharpness of successive edges.

8. That improvement in methods of detecting variations in the sharpness of blade edges which consists in directing a beam of light successively against the edges of a series of blades, and utilizing variations in the light reflected from said edges to move an indicating element in response enemas to predetermined variations in such reflected light.

9. That improvement in methods of detecting variations in the sharpness of blade edges which consists in directing a beam of light successively against the edges of a series of blades, and causing variations in the light reflected from successive edges to produce changes in an electric circuit depending upon variations in the sharpness of said edges.

10. That improvement "in methods 01 detecting variations in the sharpness of blade edges which consists in directing a beam of light successively against the edges of a series ofblades, causing variations in the light reflected from successive edges to produce changes in an electriccircuit depending upon variations in the sharpness of said edges, and utilizing said circuit changes to give indications of the condition of said edges.

11. That improvement in methods of sorting blades according to the sharpness of their edges, which consists in directing a beam of light successively against the edges of a series of blades, sorting said blades, and controlling said sorting operation in accordance with predetermined variations in the light reflected from successive edges.

12. That improvement in methods of sorting blades according to the sharpness of their edges,

which consists in directing a beam of light successively against the edges of a series of blades,

causing variations in the light reflected from successive edges to produce changes in an electric circuit depending upon variations in the sharpness of said edges, and utilizing said circuit changes to sort the blades.

1 13. In a machine of the character described, the combination of means for moving the edge of a blade through a beam of light, and means for measuring changes in the intensity oi?v the light reflected from successive portions of said edge.

14. In a machine of the character described,

the combination of means for positioning a blade, means for directing a beam of light on the edge of a blade so positioned, and means for utilizing the light reflected from said edge to indicate the degree of sharpness of the edge.

15. In a machine of the character described, the combination of means for directing a beam of light successively against the edges of a series of blades, and means for producing changes in an electric circuit depending upon variations in the light reflected by successive edges.

- 16. In a machine of the character described, the combination of means for directing a beam of light successively against the edges of a series of blades, whereby the light reflected by said edges will vary with the sharpness of the edges, means for producing changes in an electric cir-.

' the light reflected by successive edges, and mech- 'anism for utilizing predetermined changes in said current flow to sort said blades to separate the sharp blades from the dull blades.

18. In a machine of the character described,

the combination oi means for positioning a blade, means for directing a beam of light on the edge of a blade so positioned, and an electric circuit including a light sensitive resistance element arranged to receive light reflected from said edge, whereby the resistance of said element will be modified by variations in the quantity of reflected light coming to it from the direction of said edge. 19. In a machine of the character described,

the combination of means for positioning a' blade, means for directing a beam of light on the edge of a blade so positioned, an electric circuit including a light sensitive resistance element lo cated in the path of light reflected by said edge, and means for protecting said element from stray light. I I

20. In a machine of the character described, the combination oi means for positioning a blade, means for directing a beam of light on the edge of a blade so positioned, an electric circuit including a light sensitive resistance element arranged to receive light reflected from said edge, whereby the resistance of said element will be modified by variations in the quantity of reflected light coming to it from the direction of said edge, means for protecting said element from stray light, and indicating means arranged to be operated by changes of predetermined degree in the current flowing through said circuit.

21. In a machine for testing razor blades,.the combination of means for positioning a blade for the testing operation, means for directing a beam of light on the edge of a blade so positioned, a light sensitive resistance element located in the path of the rays of light coming from the direction of said edge, an electric circuit in which said element is connected, means for protecting said element from stray light, and means for auto,- matically cutting oil the light from said element when a blade is not in proper position for testing. 22. In a machine for testing razor blades, the combination of means for positioning a blade for the testing operation, means'ior directing a beam of light on the edge of a blade so positioned, a light sensitive resistance element located in the path of the rays of light coming from the direction of said edge, an electric circuit in which said element is connected, means for protecting said element from stray light, and means for automatically cutting of! the light from said element between the testing of successive blades and while the end portions of the blades move through the testing position.

23. In a machine for testing thesharpness of blade edges, the combination oi means for positioning a blade for the testing operation, means for directing a beam of light on the edge of a blade so positioned, a photo-electric cell located in the path of the light reflected from the edge of said blade, and means of protecting the cell from light reflected from parts of the blade at the ends of its edge,

24. In a machine for testing the sharpness of blade edges, the combination oi means for positioning a blade for the testing operation, means for directing a beam of light on the edge of a blade so positioned, a photo-electric ceh lccated in the path of the light reflected from the edge of said blade, a casing for protecting said cell from stray light, a shutter for controlling the admission oi light to said cell, and means'for automatically opening said shutter when a blade is placed in testing position and closing it as the blade moves out or said position. 

